As described by Cormier et al, in U.S. Pat. No. 6,394,943, in printing machines, copiers and the like, images are often formed on or transferred to a drum having a flexible or resilient outer sleeve that, from time to time, requires replacement. Typically, the sleeve is operatively supported by a metal cylinder or mandrel. In loading the sleeve onto the mandrel, it is common to inject air under the sleeve, thereby slightly expanding the sleeve diameter, while sliding the sleeve axially onto the mandrel's supporting surface. Usually, the nominal diameter of the resilient sleeve is slightly less than the mandrel diameter. Thus, upon discontinuing the airflow, the sleeve contracts onto the mandrel and forms a tight, interference fit.
There are significant costs associated with compliant sleeve design. In order to meet registration requirements high precision grinding operations are necessary to establish low run-out and surface roughness properties. The support for the sleeve member is typically a seamless metal, which adds significant cost to manufacture the sleeve. Additionally, in order to meet transfer and registration requirements, the sleeve must have a uniform diameter within narrow tolerances in order to minimize variations in overdrive and nip width. The grinding operation typically used to obtain the correct diameter is a manufacturing step adding significant cost to manufacture the sleeve. Additionally, the surface of the sleeve wears out prior to the loss of integrity to the sleeve as a whole so that more material waste than necessary is produced.
Charlebois et al, U.S. Pat. No. 6,393,226, describe a means of controlling variations of overdrive in the resilient sleeve by embedding a stiffening layer below the imaging surface in order to achieve very high quality color rendition in a color reproduction apparatus, including excellent registration in all areas of a print. Locating the stiffening layer below the imaging surface requires additional manufacturing steps, adding significant cost to manufacture the sleeve. Adding the stiffening layer to the basic sleeve design introduces additional disadvantages. Two critical grinding surfaces are present in the described design, both of which are necessary to maintain satisfactory image quality. For the inner compliant blanket portion of the roller a grinding operation is required to establish proper mating between the inner compliant blanket and the stiffening layer and minimize run-out build up to the outside compliant blanket surface. Additionally, the outer compliant blanket portion of the roller must be ground for surface roughness and run-out requirements. The preferred stiffening layer solutions utilize expensive metal seamless sleeves to meet diameter, run out, and conicity requirements for properly mating the inner and outer compliant portions of the blanket. Metal stiffening layers also contribute to higher installation forces, higher reaction forces in fixed engagement nips, and tight tolerances.
Chowdry et al, U.S. Pat. No. 6,377,772, describe an improved solution to the multi-layer roller by describing a double-sleeved roller including a rigid cylindrical core member, a replaceable removable compliant inner sleeve member in non-adhesive contact with and surrounding the core member, and a replaceable removable outer sleeve member in non-adhesive contact with and surrounding the inner sleeve member. Although the invention enables the independent replacement of the inner and outer sleeves to reduce the costs of the components, the means envisioned for installing the members increases the complexity and cost of the mandrel support apparatus and limits the range of materials that can be used to obtain a working double-sleeved roller.
Tan et al, US2005/0138809 A1 and US2005/0143240 A1, describe a sleeve member without a metal core, resulting in a reduced cost of the part. The compliant sleeve member is mounted directly on a mandrel to form an image cylinder or a blanket cylinder for use in an electrophotographic process. The sleeve still requires a uniform diameter within narrow tolerances, thus the associated cost of grinding the surface still adds significant cost to the manufacture of the sleeve. Additionally, with the unsupported sleeve solution it can be difficult to balance the need for ease of installation with the need for properly mated sleeves and cores to avoid slipping during operation.
A need exists for a novel replaceable removable double-sleeved roller (DSR) that does not require costly mandrel hardware or costly manufacturing steps while enabling the benefits of a stiffening layer in a compliant imaging roller.
In view of the forgoing discussion, an object of the present invention is to provide a simplified mounting method for double-sleeved roller members (DSM) that may be employed in an electrostatographic apparatus and methods thereof. The present invention improves on the double-sleeved roller design by enabling a method of mounting and removal of both components of a DSR configuration simultaneously.
Another object of the present invention is to reduce the cost of a DSM. The novel mounting method of this invention enables configurations of the roller design that reduce part cost by relaxing tolerances and broaden suitable material choices for the stiffening layer. An improved double-sleeved roller mounting method enables a compliant inner sleeve member (ISM) and a compliant outer sleeve member (OSM) with improved structure that lowers manufacturing costs.
Another object of the present invention is to reduce the cost of the electrostatographic apparatus for a DSR. The novel mounting method of this invention enables mounting apparatus hardware that is significantly less complex and expensive than previous disclosures envisioned. The simultaneous mounting of the ISM and OSM allow the hardware of the mandrel to be as simple as a single sleeve roller installation.
Another object of the present invention is directed at improved registration performance. The invention enables performance-improving characteristics of a stiffening layer in a compliant roller because the support layer of the outer sleeve acts as a stiffening layer when the DSM is mounted on mandrel.